1. Field of the Invention
The invention relates in general to a semiconductor structure, and more particularly to a semiconductor structure of a high side driver and method for manufacturing the same.
2. Description of the Related Art
FIG. 1 is a partial cross-sectional diagram of a semiconductor structure of a high side driver in a conventional power supply IC. Referring to FIG. 1, the semiconductor structure of a high side driver includes a high voltage (HV) junction 110 formed in a P-substrate 100 and a high voltage (HV) capacitor structure 120 formed on the P-substrate 100. The HV junction includes a deep N well (NWD) 112 and a number of P-wells (PW) 114. The HV capacitor structure 120 includes a first metal layer 122 and two separated second metal layers 124 and 126. The second metal layer 124 is connected to a low voltage, such as 0V, and the second metal layer 126 is connected to a high voltage +V, such as 500V. A heavy ion-doped N+ well 116 is formed between the P wells 114 for connecting to the second metal layer 126 via a bonding metal 130.
Basically, an over-large conductive material covered on the HV junction 110 will reduce the breakdown voltage of the HV junction 110. In order to prevent the breakdown voltage of the HV junction 110 being reduced by conductors (metals) in the HV capacitor structure 120, conventionally, the HV capacitor structure 120 is disposed in a region of the P-substrate 100 separated from that region forming the HV junction 110 as shown in FIG. 1, and is connected to the HV junction 110 via the bonding metal 130. However, the conventional semiconductor structure of a high side driver has the following disadvantages:
1. It needs more chip space to dispose the HV junction 110 and HV capacitor structure 120 in separated regions of the P-substrate 100.
2. It needs an extra bonding metal 130 for connecting the HV junction 110 and HV capacitor structure 120, and thus more cost for manufacturing the power supply IC.
3. The dielectric layer between the first metal layer 122 and the second metal layers 124 and 126 needs to have a thickness of at least 1.5 um so that the capacitor structure 120 can endure the high voltage 500V. However, too large thickness of the dielectric layer will result some issues, such as yield reduction of the power supply IC.